The invention relates to a jointing method for joining preformed bodies and to a composite of preformed bodies.
It is especially in light-weight structural engineering that has always been a problem in joining individual structuresxe2x80x94termed preformed bodies in the followingxe2x80x94in keeping with the requirements of the later application. What is required more particularly is a combination of high mechanical loading capacity and durability with minimum weight and optimum cost effectiveness for the composite and thus also for jointing. This is also basically a problem in other fields, for instance, in shipbuilding, where particularly large-area preformed bodies, for example hull segments, need to be joined to each other.
One possibility of saving weight is to make use of preformed bodies of a foamed material, more particularly of a metal foam material or fractions of such materials. Proposed in DE 43 18 540 A1 is the use of metal foam material in automobile production in which body panels are employed as foamed metal preformed bodies comprising one or two solid metal skins and a foamed layer of metal foam. For securing fitted items to these body panels mention is made of self-cutting screws and dowel-type fasteners. In the publication xe2x80x9cMetallschaume 1997xe2x80x9d, MIT Bremen, in the article entitled xe2x80x9cJoining of Aluminum Foamsxe2x80x9d by N. Sedliakova et. al., screw fasteners, soldered, cemented and welded joints as well as the use of foamed fasteners are described as methods of joining foamed metal preformed bodies. Similar is the procedure with laminated plastics/metal bodies, i.e. preformed bodies which consist of a layer of plastics and at least one layer of a metallic material. Known for these materials are rivet, screw and cemented joints.
These are the accepted methods for joining preformed bodies, the advantages and disadvantages of which are well known in engineering. Also, the joining of two or more preformed bodies made exclusively of laminated plastics bodies and even exclusively of metal by such methods is in many cases problematic.
An object of the invention is to provide a firm composite of preformed bodies and to provide a jointing technique suitable for fabricating the composite. More particularly, an intention is to enable preformed bodies of laminated composite materials to be joined together into a firm composite. Preferably, it is achieved that preformed bodies of any kind of material, even dissimilar materials can be joined together.
In a first step in accordance with the invention, the preformed bodies to be joined are located relative to each other in their position required for the composite. Preferably, they are clamped to each other. In a jointing zone in which the preformed bodies are to be joined, a space, into which the preformed bodies protrude, is encased by a jointing clamp and thus defined. The jointing clamp may be the clamping just mentioned for locating the preformed bodies prior to forming the composite, or it may be positioned not until after locating. An encasement of the encased space may be formed by the jointing clamp and the preformed bodies in common. Preferably, the jointing clamp forms the encasement by itself and the preformed bodies protrude into the space encased as defined. The encasement of this space is preferably closed on all sides, but may also, however, in principle have openings, more particularly be perforated. A filler is filled into the space encased by the jointing clamp or positioned already prior to the jointing clamp being positioned in the jointing zone, which in this case is then subsequently encased. Preferably, first the encased space is formed and then the filler is filled into the encased space. The filler is arranged such that, once the filler has consolidated, a compacting pressure materializes in the encased space which is received by the encasement and acts on the preformed bodies in the encased space, thus resulting in the preformed bodies being compacted into a solid composite by both the jointing clamp and the filler.
The filler consolidates from a preferably flowable condition. Not only a fluid material, but also a foamable material, preferably a foamable plastics material, put into the encased space for foaming and subsequently consolidated is flowable during foaming according to the invention and represents a preferred filler. In principle, it is not necessary that the filler be flowable prior to consolidating, although this is preferred. It may also be consolidated from a plastic or elastic condition by being compressed. After consolidating, the filler may be elastic, it preferably being rigid, i.e. not pliant after consolidation.
The filler is filled preferably so that it fills out the encased space totally, although in principle partial filling is sufficient to produce a reliable joint, preferably both positively and non-positively of the preformed bodies which in the anticipated loading conditions receive and transfer the forces involved. The filler urges against the encasement from within. The preformed bodies, jointing clamp and filler combine to form a compacted composite.
The jointing clamp is formed by a tubular cylindrical section or comprises a tubular cylindrical section, preferably an elongated tubular cylindrical section with which the jointing clamp forms the encased space. The jointing clamp is provided with an opening or slit in its tubular cylindrical section. The slit extends to advantage up to at least one face end of the tubular cylindrical section, and it being configured particularly preferably as a full-length slit so that the tubular cylindrical section of the jointing clamp is slit throughout longitudinally. The jointing clamp is fitted, mounted, pushed in place or otherwise located relative to the preformed bodies placed in accordance with each other on joining sections configured accordingly on the preformed bodies. In the starting position prepared for press compaction of the filler, joining sections of the preformed bodies to be jointed thus protrude into the space defined by the jointing clamp. Preferably, a joining section protrudes into the space encased by it also when a jointing clamp is configured integrally. A joining section of a preformed body may be formed at an edge of the preformed body or also at any other joining location of the preformed body serving to make the joint.
Preferably, a prefabricated separate jointing clamp is employed as the jointing clamp. This separate jointing clamp is placed on the preformed bodies to be joined by it clasping the preformed bodies or at least parts thereof. In this arrangement, the jointing clamp may already clampingly locate the preformed bodies to be joined together in their position desired for the composite relative to each other. A non-clamping application of the jointing clamp is likewise possible, however.
Should more than two preformed bodies abut in a common jointing zone, such a composite of preformed bodies may be produced particularly simply by using a separate jointing clamp. The jointing clamp provided for this purpose may be formed, for example, by a star-shaped jointing clamp section.
A preformed body preferably employed is a laminated composite comprising at least one structured layer, for example, structured honeycombed, or at least one layer of a foamed material, more particularly a foamed metal or foamed plastics material. This layer is applied to a skin of a compatible base material or is sandwiched between two such skins. A typical material pairing for a preformed body is formed by foamed aluminum and solid aluminum, foamed plastics and solid plastics, foamed plastics and solid aluminum, or a layer of structured plastics or metal in combination with solid plastics or solid metal. One, several, or each of the preformed bodies to be joined may also consist solely of a foamed material.
The invention also lends itself to advantage in fabricating preformed bodies of conventional plastics, sheet metal or other profiles, sections or shells. More particularly, it is of advantage in joining all materials which are problematic in thermal jointing methods, for example welding or soldering. In metal/plastic laminates this is clear due to the greatly differing jointing temperatures, for example in welding. In other example applications, such as for instance in joining titanium sheet preformed parts, the invention is likewise of advantage since, otherwise, such materials can be welded or soldered only in a closed inert gas atmosphere where they must remain until having cooled to ambient temperature or else oxidation would greatly detriment the material properties.
The filler involved is preferably a cold or semi-cold formable plastics material or metallic material or a combination thereof. A metallic material having a softening temperature at which the preformed bodies retain their shape and stability is flowable in accordance with the invention, namely on attaining its specific softening temperature.
Plastics material used as the filler may be a single or multi-component material, reinforced or non-reinforced, foamed material, a synthetic resin, an injection molding compound or extrusion molding compound or a combination of several of these plastics materials.
In preferred embodiments the filler is put into the encased space in a flowable condition. It is also just as possible that a filler is present in the encased space in a solid condition, for instance as a granulate, and is transformed into the flowable condition in the course of the jointing procedure. Preferably, its transformance occurs by melting or foaming. Consolidating the filler then produces the compacted composite.
For its consolidation, especially curing, the filler may be heated, although it is also just as possible to make use of a filler which consolidates at ambient temperature. If a filler is used which expands on consolidating, for example a foam material, then it suffices to simply fill the encased space with this filler to achieve a compacted composite. Should the filler not expand, or even shrink on consolidating, an expander is arranged to advantage in the encased space by means of which the filler is urged against the encasement. An expander may also be used to advantage in conjunction with a filler, which expands on consolidating, to form the compacted composite.
The expander may be a means with which the filler is filled into the encased space pressurized and held there under pressure until its consolidates. However, the expander may also be a means with which a reaction fluid is put into a filler formed by a plastics material when the filler is already located in the encased space. By the action of the reaction fluid, foaming of the plastics material is influenced, preferably controlled.Foaming may be initiated, boosted, diminished or discontinued by the reaction fluid. The reaction fluid may be in particular a foaming agent. The expander comprises in a further embodiment an expandable pressure conduit arranged in the encased space By expanding the pressure conduit, pressure is exerted on the surrounding filler, as a result of which the filler is urged against the encasement.
Advantageously, filler particles such as chopped fibers of glass, carbon or some other material may be filled together with a flowable filler or prior thereto to further enhance a non-positive and/or positive connection of the components involved in the composite.
In a preferred further embodiment, the space encased by the jointing clamp is thermally treated from within. Thermal treatment for heating or cooling, or for heating and cooling, may be formed, in principle, by any suitable kind of cooling or heating means, for example by the application of electrical energy. Preferably, at least one flow conduit is arranged in the encased space through which a cooling or heating fluid is guided. Internal thermal treatment is particularly of advantage when use is made of hot crosslinked resins, thermosetting plastics or thermoplastics formulated with foaming agents to foam at the processing temperature.
In a preferred embodiment, thermal treatment fluid is directed into the encased space in counterflow. For this purpose, two flow conduits may be oriented side by side closely spaced or in direct thermal conductive contact with each other, through which the thermal treatment fluid is passed in counterflow. In both flow conduits, thermal treatment fluid is introduced at the desired temperature and passes through in counterflow. Along the pair of flow conduits, the thermal treatment temperature materializes particularly constant. Instead of a thermal treatment fluid passing through flow conduits separately in flow, it may also be passed through the two flow conduits in sequence. In both flow guidance arrangements, the one of the two flow conduits may surround the other.
In the encased space, several of the pairs of flow conduits, as described above, may be arranged, indeed, combinations of pairs of flow conduits and single flow conduits may also be formed.
By means of a nested flow conduit configuration and guidance of the thermal treatment fluid therethrough in counterflow, the temperature of the thermal treatment means and, thus ultimately, of the foamed metal is set particularly uniformly over a long length of flow conduit. In accordance with one particularly preferred embodiment of nested flow conduits, one outer flow conduit accommodating an inner flow conduit is closed off at one end which may be located in the filler. For heating, the hot thermal treatment fluid is introduced into the inner flow conduit through which it flows, and emerges therefrom at the closed end of the outer flow conduit to enter therein before then flowing in the intermediate space between the inner and outer flow conduit back to a thermal treatment means. During this, a compensation in the heat occurs between the thermal treatment fluid in the inner flow conduit and the return flow of thermal treatment fluid. This results in a particularly uniform temperature of the return flow of the thermal treatment fluid over the full length of the flow conduit.
Instead of the blind thermal treatment means as described above, in which the thermal treatment fluid is led in and out at the same end, the thermal treatment fluid may also be led in and out at the opposite ends of these flow conduits in each case. This is only possible, however, when the inner and outer flow conduits are brought out at both ends from the encased space. Accordingly, in the following, reference is made simply in general to an outer flow of fluid instead of a return flow of fluid.
The inner flow conduit is preferably located over its full length centrally spaced away from the outer flow conduit. This may be achieved by means of spacers arranged between the inner flow conduit and the outer flow conduit. These spacers are made of a heat resistant material, for instance of ceramics.
Preferably, the outer flow of the thermal treatment fluid is turbulent, as a result of which the heat conducted from the inner flow conduit into the outer flowing thermal treatment fluid and from the outer flowing thermal treatment fluid to the filler is enhanced as compared to that of a laminar flow. The spacers may be configured accordingly as the means for producing turbulence. It is particularl preferred to produce the turbulent outer flow by means of a tape, wound spirally around the inner flow conduit. In a preferred embodiment, such a tape simultaneously serves as a spacer, i.e. no further spacers are needed in addition thereto. Preferably, the tape is configured as a woven tape, more particularly of heat resistant fibers such as e.g. glass, ceramic or carbon fibers. Due to the tape being wound spirally around the inner flow conduit, the thermal treatment fluid is, likewise, guided and swirled spirally in the intermediate space between the inner and outer flow conduit.
In the event of using nested flow conduits, the outer flow conduit may remain in the filler structure upon completion of consolidation. The remaining outer flow conduit improves the mechanical properties of the preformed body, especially when the internal thermal treatment is undertaken in a jointing zone of several preformed bodies. The inner flow conduit as well as the spacers, or the fiber tape, may be preferably removed from the outer flow conduit to be available for repeat use. The inner flow conduit and the spacers, or the fiber tape replacing the spacers, may, likewise, remain in the encased space, however. By preferably filling out the cavity, surrounded by the outer flow conduit, with plastics material, the preformed body or the composite zone may be further reinforced mechanically. It is particularly preferred to make use of a flow conduit or nested flow conduits made of carbon fiber material, thus resulting in a carbon-reinforced composite.
A thermal treatment system comprises preferably an internal combustion engine with a turbocharger, the exhaust air being employed as the heating fluid, the intake air to the charger being used as the cooling fluid. The force driving the engine may be used to generate electricity.
A flow conduit, arranged in the jointing zone, may be made use of not only for thermal treatment but also, or instead thereof, for bringing in materials, particularly fillers. It may be used to advantage to impregnate a bundle of reinforcement fibers or a composite of fiber bodies, more particularly with a fluid plastics material, a binding agent or a reaction fluid. The fluid involved is advantageously conveyed by means of a pump through the fiber composite until complete saturation of the fibers of the bundle or of the fiber composite and filling of the encased space is assured.
Where several flow conduits are configured in the jointing zone, multi-component plastics, more particularly two-component plastics, for example resin and a hardener, may be brought into the encased space and sited to react.
A flow conduit serving to place material in the encased space is provided preferably with a plurality of openings, i.e. perforated, to bring a thermal treatment fluid, binding fluid or reaction fluid, evenly distributed, into contact with the plastics material, or to bring in the plastics material itself.
In preferred embodiments, a pressure conduit, expandable by internal pressure, is arranged in the encased space. The plastics material present in the encased space or part thereof is urged against the encasement by the expanded pressure conduit. By making use of such an expander, fillers subject to a reduction in volume during consolidation are also available for a compacted composite in accordance with the invention.
Filling and consolidating such materials in pressurizing the encased space in all, as likewise possible in principle, is not necessary. The filler is urged particularly uniformly against the defining surface areas of the encased space, any tendency to shrinkage being reliably compensated.
In preferred variants of the method in accordance with the invention, the pressure conduit is cyclically impinged with alternating pressure and temperature. Due to such a process of temperature and pressure change, preferably a plastics material, brought into the encased space, having reinforcing components, e.g. an epoxy resin/carbon fiber matrix is consolidated. Implementing reproducible alternating temperature and pressure cycles permits a particularly uniform curing and consolidation of the filler filled into the encased space. In the varying pressure cycles, overpressure and vacuum alternate to advantage as measured relative to the environment. Any gas pockets, in particular trapping of air in the filler, more particularly in a fluid filler such as, for example, synthetic resin, are eliminated by generating a vacuum in the encased space.
In a preferred first aspect, a tubular pressure conduit is formed by a flexible material, for example silicone. A pressure conduit of an elastic material is particularly of advantage for pressure alternation.
In a preferred second aspect, the tubular pressure conduit is formed by a cold-formable metal, a material suitable in this respect being e.g. AlMg5MnN. By charging the pressure conduit with a sufficiently high internal pressure, it is expanded to such an extent that a solid compacted composite materializes. In the scope of the deformation, the apparent yielding point of the metal forming the pressure conduit is exceeded to such an extent that no return formation occurs in the range of application temperatures of the composite of preformed bodies. The jointing clamp, and to a lesser extent also the preformed bodies, limit the deformation of the pressure conduit.
By heating the pressure conduit, especially by means of a heated pressurizing fluid, expansion may also be made by way of a semi-cold forming procedure; significantly lower fluid pressures can then be worked with when heating is applied, so that correspondingly less force needs to be handled by the jointing clamp in order to accommodate the increase in the internal pressure. As evident from the flow curves, for example of the material AlMg5MnN, the logarithmic forming limit may be doubled at temperatures of around 200xc2x0 C. under the conditions of uniform stretcher-level. Semi-cold forming is done preferably at a temperature within the range of 100 to 300xc2x0 C.
It is particularly of advantage for the combination of materials when the softening temperature of the pressure conduit material equals the melting temperature of the filled filler, which is preferably a plastics material. The softening temperature of the pressure conduit and the melting temperature of the filler should be lower than the first glow temperature (Losglxc3xchtemperatur) and the melting temperature of the materials of the preformed bodies and the jointing clamp respectively.
On expansion of a pressure conduit in the encased space, the jointing clamp is designed preferably so stiff that it accommodates the resulting pressure load without deforming. In an advantageous dual function, a flow conduit for a thermal treatment fluid doubles as the pressure conduit which brings about, or assists in bringing about, compacting in the encased space. In addition to the flow conduit, which is preferably made from a cold-formable metal, for example AlMg5MnN, a thermoplastic material, for example polyamide or thermoplastic polyurethane, with or without a reinforcement material, is brought into the encased space between the conduit and the encasement. Subsequently, the fluid in the flow conduit is heated to the processing temperature of the plastics material, for example in the case of polyamide, to a temperature ranging from 185 to 240xc2x0 C. Once the melting temperature of the thermoplastic has been attained, the pressure conduit is charged with the pressure necessary for its semi-cold forming. The pressure conduit expands and fills out the encased space together with the melted plastics material. Upon maintenance of the pressure, the pressure conduit is led into a dimensionally stable phase by the introduction of a cooling fluid. This results in a stable compacted composite.
Producing the compacted composite of preformed bodies by cold or semi-cold forming of a pressure conduit, inserted in the encased space, may also be used alone to produce the composite of preformed bodies, although combining it with a filler, compacted thereby and which is in a flowable condition, is particularly preferred.
It is of advantage when the plastics material seals off the compacted composite. Metallic components in the encased space are thus protected from the ingress of aggressive media, and an uncontrolled corrosion in the interior of the compacted composite is prevented. Thermoplasts employed for this purpose are preferably hydrolysis-stable, for example, thermoplastic polyether-based polyurethane. Thermoplastic polyurethanes (TPU) are also of advantage in this respect since they tend to adhere to the metallic surfaces in the course of the melting procedure.
Making use of thermoplasts as the filler also has the advantage, apart from the special application as cited above, that profiles of any shape, for example extruded profiles, can be formed. In one preferred further development, one such profile, or several such profiles, is/are inserted into the encased space between jointing clamp and preformed body. Preferably, in a previous step, the flow conduit is inserted into a cavity of the thermoplastic profile provided for this purpose, so that flow conduit and thermoplastic profile can be inserted into the encased space in a single step. The thermoplastic profile is preferably designed to be used simultaneously as a spacer for centering the flow conduit in the encased space and doubling as a spring element prelocating the composite of preformed body and jointing clamp in the desired position.
This arrangement is also of advantage in joining curved profiles and preformed bodies, since in this case a specific clearance is needed between preformed bodies and jointing clamp to compensate any possible differing radii, in particular differing bending radii. Prior to final fabrication of the compacted composite, it is assured that the preformed bodies and the jointing clamp or a plurality of jointing clamps are correctly located.
In a preferred aspect, an insertion profile, more particularly a thermoplastic profile, is used to separate non-compatible materials, such as for example stainless steel and aluminum, and to prevent galvanic contact corrosion. For this purpose, the insertion profile is configured such that it totally covers the contact surface areas between preformed bodies and jointing clamp and/or to a flow conduit to be expanded and, thus, form an isolating barrier layer.
It is of advantage when prior to, during, or after positioning of the jointing clamp, a reinforcing structure, or a plurality of reinforcing structures, is/are placed into the jointing zone in addition to the already reinforcing jointing clamp, as a result of which the jointing zone may be enhanced with additional functions. The reinforcing structure is preferably a preformed fiber composite, adapted to the encased space, its fibers being made of plastic, glass, ceramics, mineral, carbon or metal or a combination thereof, said fibers being embedded in a plastics matrix, or a fiber string into which individual fibers are bundled, for example interwoven or only intertwined.
Preferably, once the reinforcing structure has been put into the encased space, the encased space with the reinforcing structure is totally filled with a hot cross-linking resin blend, for example an epoxy resin, preferably at room temperature. This is achieved preferably by means of a pump, for instance a rotary flexible pump, which pumps the resin into the encased space, until the vacuum generated by the pump causes the resin to reemerge from the suction side of the encased space.
When this system works in a closed pump circuit, it is possible to put the required amount of resin into the encased space by a simple volume calculation. It is of advantage that, after the reinforcing structure has been totally impregnated, the residual volume can be reduced to the calculated amount by pumping off the excess resin. Checking the remaining amount of resin can then be simply done by checking the level of the resin in a transparent catchment vessel. At the same time in this procedure, the encased space is evacuated to thus minimize the risk of air inclusions, i.e. blowholes in the resin.
In a subsequent preferred step, a flow conduit is used as a thermal treatment conduit, it being filled with a thermal treatment fluid and heated in a closed circuit to a temperature below the cross-linking temperature of the resin. When an epoxy resin is taken as an example, which cures at 175xc2x0 C., the thermal treatment fluid is heated to approximately 160xc2x0 C. Once the thermal treatment fluid has attained this target temperature throughout, the flow conduit is used as a pressure conduit and thus is pressurized until a reshaping process commences. In this respect, the pressure needed depends on the material of the flow conduit. If a flow conduit made of AlMg5MnN (EN AW-5182-0) is used, then the pressure should be around 220-240 MPA. In the course of this semi-cold formation, the flow conduit expands and totally fills the encased space together with the surrounding resin/reinforcing fiber matrix. In a preferred subsequent step, the temperature is increased to the cross-linking temperature of the resin, 175xc2x0 C. in the previous example, and maintained at this temperature according to the manufacturer""s standard time for curing the resin. Meanwhile, the temperature remains unchanged. After curing, the fluid can be cooled to room temperature or replaced by a fluid at room temperature. The pressure is reduced to, finally, empty the flow conduit.
In further steps this method may also be employed to subject the materials used to consolidate the material composite to a subsequent temperature or pressure treatment.
More particularly, more than two preformed bodies may also be joined. For this purpose, a multi-legged bridging element is employed in the zone where the preformed bodies intersect. If pressure conduits are made use of for jointing, is assured while locating the bridging element that intersecting flow conduits cannot squeeze each other on expansion which would choke off the conduit flow. This is assured by the bridging element accommodating the pressure conduits in different levels and restricting expansion of the pressure conduits. The pressures conduits are able to expand into undercuts, preferably configured in the bridging element, to thus be anchored in place thereby.
In all embodiments of the invention, a closure profile may be arranged in a longitudinal slit between the preformed bodies, abutting otherwise therein, level with their plane of contact. The closure profile may serve as a sealing profile or a compensating profile or as a supporting profile or fulfill a combination of these functions.
It is of advantage when the closure profile seals off the encased space longitudinally, thus enabling materials of low viscosity to be more easily processed in the encased space. By means of the closure profile, preformed bodies having joining profiles differing in thicknessxe2x80x94for example a single-layer and a multi-layer preformed bodyxe2x80x94can be more simply joined by a single shape and size of jointing clamp since the closure profile evens out the differences. It is likewise of advantage that, due to a closure profile, a smooth surface is achievable at an outer contour opposite the encased space, for example on vehicles, requiring a smooth outer contour for streamlining.
For certain applications of the composite of preformed bodies it is of advantage when a closure profile has good thermal conductivity. The closure profile, and preferably a flow conduit being used in conjunction, may then be used for thermal treatment, namely for cooling and/or heating a preformed body of the composite. In this arrangement, heat may be directed either from the corresponding preformed body into the flow conduit or vice-versa and received or given off from a fluid in the flow conduit.
Where large preformed bodies are concerned, for example in sailing boat hull structures in the region of shroud and freight container lashing points or aircraft wings, it may be necessary to introduce high forces into the preformed body. For this purpose, a reinforcing structure, arranged in the encased space, may be used in accordance with the invention which, more particularly, may be formed by a fiber bundle or a fiber composite body, but also by a flow conduit. The reinforcing structure is led out from the preformed body composite at one or more suitable points and preferably configured into a lashing point, for example in the form of a lug. Provided preferably where the reinforcing structure is led out is a cap profile or cap section directly clasping the joining profiles of the preformed bodies or preferably the jointing clamp. When a fiber composite body forms the reinforcing structure this preferably constitutes a resin-impregnated fiber composite body, a so-called prepreg. The jointing clamp may also already serve as the reinforcing structure, preferably, however, a reinforcing structure is arranged in the mechanical uncritical zero position of the jointing zone so that it forms a neutral filament or core.
By means of the invention it is now possible to make specific use of the jointing zone of preformed bodies as the reinforcing element of the composite of preformed bodies. The compacted composite in the encasement formed by the jointing clamp already forms a reinforcement of the composite, especially where large structures are concerned. Thus, the jointing zone in accordance with the invention is able to assume the structural-reinforcing function of frames and stringers and can replace such frames and stringers, for example in aircraft and marine engineering or also in automotive engineering where comparable structural-reinforcing members are employed. Particularly suitable for an application of such reinforcing members is a jointing zone in accordance with the invention which has a reinforcing structure, such as for example a fiber composite body or a fiber bundle inserted therein.
Jointing in accordance with the invention proves to be particularly of advantage when the preformed bodies consist of laminates having metal skins. As already mentioned at the outset, prior art jointing techniques pose considerable problems where laminates are concerned since they add to the risk of fracture or rupture. Surface jointing of fiber prepregs and metallic skins is critical due to the poor adhesion between metal and plastic. In addition to this, pretreating the metallic skins with aggressive cleaning and coating agents detriments the properties of these metallic skins. These problems are obviated by the solution in accordance with the invention.
A flow conduit, more particularly a metallic flow conduit, serving as the thermal treatment conduit and/or pressure conduit in producing the composite, may used to advantage for thermal treatment, namely for cooling and/or heating a preformed body of the composite in later applications, especially in aeronautical and aerospatial applications of the composite. Heat may be communicated either from the corresponding preformed body into the flow conduit or vice-versa and received or given off by a fluid in the flow conduit. Instead of thermal energy, or also in combination therewith, the flow conduit may also be used for transporting electrical energy and/or data communication.
By introducing a cooled fluid into a flow conduit, arranged in the jointing zone, the complete jointing zone may be cooled and, thus, the strength of the joint is also assured even at high temperatures of the preformed body. Just as possible is the protection of sections of an aircraft exposed to icing by introducing a heated fluid into the flow conduit. For this purpose, heated cooling water of a vehicle engine, an air-conditioning system or some other assembly may be introduced into the flow conduit and the heat energy given off to the outer contour of the preformed body.